<script type="text/javascript">
function setScrollbarColor()
document.body.style.scrollbarBaseColor="green";
<input type="button" onclick="setScrollbarColor()" value="Set ScrollbarColor" />
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>